My boyfriend has just gone on a business trip which an ex will be on - how do I keep him thinking about me?

A few months ago I found some emails from my boyfriend to an ex-lover of his whom he still works with. In the emails he asked her to go on webcam for him, however the conversation ended before anything happened. I confronted him about this and after much deliberation decided to forgive him as I knew he was truly sorry and had never done anything like this before. However now he has gone away for two days on a business trip which she will be on (staying in the same hotel). I'm learning to trust him again, however I still cant help worrying about them being away together. What should I do while he's away to keep him thinking about me. I don't want to text and call constantly while he is busy and annoy him, but I want him to be thinking about me. I thought about sending him some texts but I don't want to get him riled up around her. Any help?